//
//   Code taken and adapted from CodaEffects.js - (C) 2007 Panic, Inc.
//   http://www.panic.com
//  
// 
//

var currentSection = "home-pane"; // The default loaded section on the page
var tabTag = "-tab";
var paneTag = "-pane";

// Scroll the page manually to the position of element "link", passed to us.

function ScrollSection(link, scrollArea, offset)
{

  // Store the last section, and update the current section

  if (currentSection == link) {
    return;
  }
  lastSection = currentSection;
  currentSection = link;
  
  // Change the section highlight.
  // Extract the root section name, and use that to change the background image to 'top', revealing the alt. state

    sectionTab = currentSection.split("-")[0] + tabTag;
    document.getElementById(sectionTab).className = 'active';
    if (lastSection) {
      lastTab = lastSection.split("-")[0] + tabTag;
      document.getElementById(lastTab).className = "inactive";
  }
    
  // Get the element we want to scroll, get the position of the element to scroll to
  
  theScroll = document.getElementById(scrollArea);
  position = findElementPos(document.getElementById(link));
  
  // Get the position of the offset div -- the div at the far left.
  // This is the amount we compensate for when scrolling
  
  if (offset != "") {
    offsetPos = findElementPos(document.getElementById(offset));
    position[0] = position[0] - offsetPos[0];
  }

  
  scrollStart(theScroll, theScroll.scrollLeft, position[0], "horiz");
  // return false;
}

function ScrollArrow(direction, toolbar, scrollArea, offset) {

  toolbarElem = document.getElementById(toolbar);
  toolbarNames = new Array();
    
  // Find all the <li> elements in the toolbar, and extract their id's into an array.
    
  if (toolbarElem.hasChildNodes())
  {
    var children = toolbarElem.childNodes;
    for (var i = 0; i < children.length; i++) 
    {
      if (toolbarElem.childNodes[i].tagName == "LI") {
        toolbarNames.push(toolbarElem.childNodes[i].id.split("-")[0]);
      }
    }
  }

  // Now iterate through our array of tab names, find matches, and determine where to go.

  for (var i = 0; i < toolbarNames.length; i++) {
    if (toolbarNames[i] == currentSection.split("-")[0]) {
      if (direction == "left") {
        if (i - 1 < 0) {
          gotoTab = toolbarNames[toolbarNames.length - 1];
        } else {
          gotoTab = toolbarNames[i - 1];
        }
      } else {
        if ((i + 1) > (toolbarNames.length - 1)) {
          gotoTab = toolbarNames[0];
        } else {
          gotoTab = toolbarNames[i + 1];
        }
      }
    }
  }
  
  // Go to the section name!
  
  ScrollSection(gotoTab+paneTag, scrollArea, offset);

}

var scrollanim = {time:0, begin:0, change:0.0, duration:0.0, element:null, timer:null};

function scrollStart(elem, start, end, direction)
{
  //console.log("scrollStart from "+start+" to "+end+" in direction "+direction);

  if (scrollanim.timer != null) {
    clearInterval(scrollanim.timer);
    scrollanim.timer = null;
  }
  scrollanim.time = 0;
  scrollanim.begin = start;
  scrollanim.change = end - start;
  scrollanim.duration = 25;
  scrollanim.element = elem;
  
  if (direction == "horiz") {
    scrollanim.timer = setInterval("scrollHorizAnim();", 15);
  }
  else {
    scrollanim.timer = setInterval("scrollVertAnim();", 15);
  }
}

function scrollVertAnim()
{
  if (scrollanim.time > scrollanim.duration) {
    clearInterval(scrollanim.timer);
    scrollanim.timer = null;
  }
  else {
    move = sineInOut(scrollanim.time, scrollanim.begin, scrollanim.change, scrollanim.duration);
    scrollanim.element.scrollTop = move; 
    scrollanim.time++;
  }
}

function scrollHorizAnim()
{
  if (scrollanim.time > scrollanim.duration) {
    clearInterval(scrollanim.timer);
    scrollanim.timer = null;
  }
  else {
    move = sineInOut(scrollanim.time, scrollanim.begin, scrollanim.change, scrollanim.duration);
    scrollanim.element.scrollLeft = move;
    scrollanim.time++;
  }
}

function findElementPos(elemFind)
{
  var elemX = 0;
  var elemY = 0;
  do {
    elemX += elemFind.offsetLeft;
    elemY += elemFind.offsetTop;
  } while ( elemFind = elemFind.offsetParent )

  //console.log("Found element "+elemFind+" at "+elemY+"/"+elemX);

  return Array(elemX, elemY);
}

function sineInOut(t, b, c, d)
{
  return -c/2 * (Math.cos(Math.PI*t/d) - 1) + b;
}
